1. Field of the Invention
The present invention relates to a flexible tube for an exhaust pipe of an automobile, and more particularly to, a flexible tube for an exhaust pipe of an automobile, wherein a depression inner diameter in the center of a bellows is formed to be larger than a depression inner diameter at both sides of the bellows such that a gap from an interlocking member increases so as to prevent the interference between the bellows and the interlocking member, thereby improving traveling noise, while both end parts have a small gap so as to increase the height of protrusions, thereby improving the flexibility and durability of the bellows.
2. Description of the Related Art
In general, an exhaust pipe is connected to the engine of an automobile so as to discharge exhaust gas, wherein a flexible coupling is mounted on the connection portion thereof such that the flexible coupling absorbs external force which is generated from the vibration of the engine and the vibration of the surface of a road so as to extend the lifespan of the exhaust pipe and to improve the ride comfort.
The flexible coupling which is connected to the exhaust pipe of an automobile as above generally absorbs the tension, compression and bending displacement which are generated in response to the movement of an exhaust system from the engine vibration and the road surface vibration, wherein torsion displacement generated in every direction may follow according to the mounting conditions of the engine, the direction where the displacement generates, and the design and shape of the entire exhaust pipe.
Therefore, a bellows made from a metal material is mainly used in order to improve the performances for maintaining airtightness and absorbing vibration and displacement, which are the core functions of the flexible coupling for an exhaust pipe of an automobile.
In addition, the flexible coupling is provided with an interlocking member as disclosed in EP 041089 A1, such that the interlocking member simultaneously absorbs the inward axial deformation, bending deformation or the like of a bellows member which is made from a metal material in the shape of a cylinder with repetitive corrugations, controls displacement within the range of elastic limit of the bellows member, makes the flow of exhaust gas smooth as a guide pipe, and protects the bellows member from the exhaust gas of high temperature.
Further, the bellow member is formed in a structure, wherein the outside portion of the bellows member is surrounded by a braid member and, in this situation, the both ends of the bellows member and the braid member are compressed together with caps in the circumferential direction so as to be finished by spot-welding.
That is, one end is coupled to an engine side and the other end is coupled to an exhaust pipe side such that the exhaust gas passes through a center portion and the bellows member and the interlocking member absorb shocks, deformation or the like which acts between the engine and the exhaust pipe via contraction and expansion.